• Journal of Broadcast Engineering
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• v.22 no.3
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• pp.295-312
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• 2017

Digital video content is the most information-intensive and high-value content. Therefore, it is necessary to protect the intellectual property rights of these contents, and this paper also proposes a watermarking method of digital image for this purpose. The proposed method uses the frequency characteristics of 2-Dimensional Discrete Wavelet Transform (2D-DWT) for digital images and digital watermark on global data without using local or specific data of the image for watermark embedding. The method to insert digital watermark data uses a simple Quantization Index Modulation (QIM) and a multiple watermarking method that inserts the same watermark data in multiple. When extracting a watermark, multiple watermarks are extracted and the final watermark data is determined by a simple statistical method. This method is an empirical method for experimentally determining the parameters in the watermark embedding process. The proposed method performs experiments on various images against various attacks and shows the superiority of the proposed method by comparing the performance with the representative existing methods.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.195-195
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• 2019

최근 센싱 기술과 정보화의 영향으로 하천에서 발생하는 다양한 정보들이 디지털화되어 저장되고 있으며, 이를 효율적으로 저장하고 관리하고자 하는 연구가 수행되고 있다. 특히, 과거에는 점, 선, 면으로 구성된 자료 위주로 구성되어 있어 수집된 자료를 주제별로 관리하는 레이어 형식으로 저장하여 자료를 표출하기 위한 목적으로 설계되었지만, 최근에는 영상자료, 시계열자료 등 기존의 자료와 다른 비구조적 형태의 자료가 발생함에 따라 하천 네트워크를 기반으로 한 하천공간정보를 관계형 구조로 설계하고 있다. 하천의 경우, 각 하천공간정보가 가지는 고유의 값을 활용하여 인접한 하천 네트워크를 구성하는 하천의 중심선 혹은 최심선을 기준으로 하천공간정보들을 관계성을 부여한다. 하지만 이러한 관계성은 자료의 저장, 관리, 제공에는 유리한 측면이 있지만 기하학적인 고려가 없기 때문에 공간정보로서 활용하기에는 한계가 존재한다. 쉽게 설명하면, 1차원 점에 해당하는 공간좌표는 가장 가까운 하천 네트워크를 대상으로 관계성 부여가 가능하지만, 2차원 선과 3차원 면에 해당하는 도형을 대표하는 위치가 공간적으로 많기 때문이다. 본 연구에서는 하천 네트워크 기반 공간정보가 관계성을 부여하되 하천공간정보가 가지는 기하하적 구조를 반영하기 위해 하천 네트워크를 중심으로 한 곡선좌표계 부여 방법을 제시하고자 한다. 하천은 실제로 연속적으로 변화하며, 곡선으로 이루어져 있기 때문에 공간적으로 직교좌표계를 활용하기 보다는 곡선좌표계를 활용하는 것이 더 적합한 것으로 알려져 있다. 실제로 많은 수치해석 모형에서는 곡선좌표계를 고려하여 수치해석을 수행하고 있으며, 도로나 교통 분야의 공간정보에서도 공간적 고려를 위해 곡선좌표계를 활용하는 것으로 알려져 있다. 본 연구에서는 하천 중심선 혹은 최심선을 기준으로 흐름방향 거리를 S, 횡방향 거리를 N으로 설정하여 곡선좌표계를 정의하였으며, 직교좌표계와 곡선좌표계간의 좌표변환을 위해 이차원 변환방법인 투영변환을 활용하였다. 본 연구에서 제시된 방법을 활용할 경우, 하천 네트워크 기반 공간정보가 자료 간의 관계성을 유지하며, 기하하적 고려가 될 것으로 사료된다.

• Journal of the Korea Society of Computer and Information
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• v.14 no.2
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• pp.45-57
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• 2009

ETexture mapping is a technique used for adding reality to an image in 3D graphics. However. this technique becomes the bottleneck of the 3D graphics pipeline because it requires large processing power and high memory bandwidth. For reducing memory latency in texture mapping, texture cache is used. As portable devices become smaller and they have power constraint, it is important to reduce the area and the power consumption of the texture cache. In this paper we propose using a small texture cache to reduce the area and the power consumption of the texture cache. Furthermore, we propose techniques to keep a performance comparable to large texture caches by using prefetch techniques and a victim cache. Simulation results show the proposed small texture cache can reduce the area and the power consumption up to 70% and 60%, respectively, by using $1{\sim}2K$ bytes texture cache compared to the conventional 16K bytes cache while keeping the performance.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.10
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• pp.465-472
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• 2015

We propose a novel plane detection in disparity space and evaluate its performance. Our method simplifies and makes scenes in disparity space easily dealt with by approximating various surfaces as planes. Moreover, the approximated planes can be represented in the same size as in the real world, and can be employed for obstacle detection and camera pose estimation. Using a stereo matching technique, our method first creates a disparity image which consists of binocular disparity values at xy-coordinates in the image. Slants of disparity values are estimated by exploiting a line simplification algorithm which allows our method to reflect global changes against x or y axis. According to pairs of x and y slants, we label the disparity image. 4-connected disparities with the same label are grouped, on which least squared model estimates plane parameters. N plane models with the largest group of disparity values which satisfy their plane parameters are chosen. We quantitatively and qualitatively evaluate our plane detection. The result shows 97.9%와 86.6% of quality in our experiment respectively on cones and cylinders. Proposed method excellently extracts planes from Middlebury and KITTI dataset which are typically used for evaluation of stereo matching algorithms.

• Journal of the HCI Society of Korea
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• v.2 no.1
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• pp.25-31
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• 2007

We develop an interactive relighting renderer allowing camera view changes based on a deep-frame buffer approach. The renderer first caches the rendering parameters for a given 3D scene in an auxiliary buffer with the same size of the output image. The rendering parameters independent from light changes are selected from the shading models used for shading pixels. Next, as the user interactively edits one light at one time, the relighting renderer instantly re-shades each pixel by updating the contribution of the changed light with the shading parameters cached in the deep-frame buffer. When the camera moves, the cache values should be re-computed because the currently cached values become obsolete. We present a novel method to synthesize them quickly from the cache images of the user specified cameras by using an image-based technique. This computations are all performed on GPU to achieve real-time performance.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.4
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• pp.386-392
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• 2002

Ultrasonic has been proposed as an attractive means of detecting bone loss. There have been several commercial ultrasound devices developed for measuring the heel to predict fracture at other bones. However, these devices select only single point of heel bone as measurement site. It causes poor assessment of bone quality due to the error of transducer positioning. In an effort to improve current ultrasound systems, we evaluated the linear scanning method which provides better prediction of bone quality and an accurate image of bone shape. The system used in this study biaxially scans a heel bone using automated linear scanning technique. The results demonstrated that the values of ultrasound parameters varied with different positions within bone specimen. It has been also found that the linear scanning method could better pre야ct bone quality, eliminating the error of transducer positioning.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.3 s.357
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• pp.105-110
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• 2007

We have built the millimeter-wave passive imaging system with a lens and mechanical scan antenna. The lens was designed based on optical theory in order to focus millimeter-wane. A full image was taken from image points scanned by Placing antenna at the representative focal plane selectively. An integrated antenna array device for low-loss and low-noise with the array of 4 by 1, where components such as antenna, balun, MMIC, and detector were assembled on a sin91e substrate, and a fermi tapered slot antenna with high-gain and low-side lobe were used for elements of this millimeter-wave passive imaging system. Two dimensional antenna arrangement on focal plane was achieved in this imaging system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.3
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• pp.288-296
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• 1992

This paper describes an improved 2D QPS(quadrature polar separable) filter design and its applications to texture processing. The filter kernel pair consists of the product of a radial weighting function based on the finite PSS (prolate spheroidal sequences) and an exponential at tenuation function for the orientational angle. It is quadrature and polar separable in the frequency domain. It is near optimal in the energy loss because we let the orientational angle function approximate the radial weighting function. The filter frequency characteristics is easy to control as it depends only upon the design specifications such as the bandwidth, the directional angle, the attenuation constant, and the shift constant of the central frequency. Some applications of the filter in texture processing, such as the generation of the texture image, the estimation of orientation angles, and the segmentations for the synthetic texture image, are considered. The result shows that the filter with the wide bandwidth can be used for the generation of discrimination of the strong orientational textures and the segmentation results are good.

• The korean journal of orthodontics
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• v.39 no.6
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• pp.354-361
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• 2009

Objective: Miniscrews are widely used in orthodontic treatment for the purpose of anchorage control. Maximum anchorage can be acquired by the use of miniscrews. Maxillary miniscrew has many clinical advantage for orthodontic treatment. Maxillary sinus, tooth root can be an obstacle for maxillary miniscrew installation. The purpose of this study was to find the safest area and direction of miniscrew insertion in consideration of the maxillary sinus. Methods: The maxillary sinus area of 40 patients (20 male, 20 female) was measured using 3D computed tomography and 3D reconstruction program. Results: The maxillary sinus floor was located most inferiorly between the 1st molar and 2nd molar and located most superiorly between the 1st premolar and 2nd premolar. Buccal bone thickness from the maxillary sinus is significantly thicker between the 1st molar and 2nd molar and significantly thinner between the 1st premolar and 2nd premolar. The area between the 1st premolar and 2nd premolar has a significantly longer vertical distance from CEJ to sinus in consideration of buccal bone thickness. Conclusions: Considering maxillary bone thickness, the posterior area has advantages over the anterior area for installing miniscrews safely and preventing perforation.

• Journal of Cadastre & Land InformatiX
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• v.48 no.2
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• pp.213-225
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• 2018

For constructing three-dimensional (3D) spatial information occlusion region problem arises in the process of taking the texture of the building. In order to solve this problem, it is necessary to investigate the automation method to automatically recognize the occlusion region, issue it, and automatically complement the texture. In fact there are occasions when it is possible to generate a very large number of structures and occlusion, so alternatives to overcome are being considered. In this study, we attempt to apply an approach to automatically create an occlusion region based on learning by patterning the blocked region using the recently emerging deep learning algorithm. Experiment to see the performance automatic detection of people, banners, vehicles, and traffic lights that cause occlusion in building walls using two advanced algorithms of Convolutional Neural Network (CNN) technique, Faster Region-based Convolutional Neural Network (R-CNN) and Mask R-CNN. And the results of the automatic detection by learning the banners in the pre-learned model of the Mask R-CNN method were found to be excellent.